Where \(S_i\)  is a random subset of inputs of size \(n\) , and \(r(X,Y)\)  is the Pearson correlation coefficient between variables \(X\)  and \(Y\) . The correlation is computed using \(k\)  randomly selected subsets \(S_i\) . We choose \(k=100\) , which corresponds to the configuration in [1]}.
